Add real time feed api sample code

[cwxie-google]

We're having 5 new apis and I'm adding php sample code for those new five apis.

[cwxie-google]

@bshaffer Hi Brent, could you please take a look at this PR or assign to the right one to review it?
Thanks

[bshaffer]

Good stuff! mostly minor changes to the sample formats and variable name consistency.

[bshaffer]

nit: whitespace here

[bshaffer]

nit, but let's have this ordered better, like this:

    $pubsubDestination = (new PubsubDestination())
        ->setTopic($topic);

    $feedOutputConfig = (new FeedOutputConfig())
        ->setPubsubDestination($pubsubDestination);

    $feed = (new Feed())
        ->setAssetNames($assetNames)
        ->setFeedOutputConfig($feedOutputConfig);

[bshaffer]

casing should be deleteFeed

[bshaffer]

casing should be createFeed

[bshaffer]

casing should be getFeed

[bshaffer]

No feeds were actually listed, would probably make more sense like this:

$feeds = $client->listFeeds($parent);

printf('Feeds for %s:' . PHP_EOL, $parent);
foreach ($feeds as $feed) {
    print($feed->getName() . PHP_EOL);
}

[bshaffer]

casing should be updateFeed for the method call and $updatedFeed for the variable

[bshaffer]

Let's be consistent with our casing and make this variable $newFeed

[bshaffer]

Let's make this 'Feed Updated: ' . $updatedFeed . PHP_EOL;. All echo/print statements should have an appended new line.

[bshaffer]

Similar issue here, let's format these like follows:

    $newFeed = (new Feed())
        ->setName($feedName)
        ->setAssetNames($assetNames);

    $updateMask = (new FieldMask())
        ->setPaths(['asset_names']);

[meredithslota]

This PR is quite stale at this point, and the Asset API has autogenerated samples that also cover these use cases here: https://github.com/googleapis/google-cloud-php/tree/main/Asset/samples/V1/AssetServiceClient Closing this accordingly, please reopen if this is still active.